Question

I don’t care about which key was pressed, or how long, or anything like that. All I need is a way to detect that the user has touched the screen, even if that happens to be on the part of the screen covered by a keyboard.

My goal here is to detect a lack of interaction to ‘reset’ the app to a default state if left along long enough — think a ‘kiosk mode’ application. The issue is that I can’t detect when the keyboard is touched, as the keyboard apparently intercepts all touch events, even before my customer window can handle them.

Edit:

Considered (and dismissed) is the use of just keyboard show and hide notifications — we need to prolong screen display if the user is actively typing. Since we use UIWebViews to display certain things, we also can’t use the delegate methods of UITextViews or UITextFields.

Answer 1

It sounds like detecting all touches—on the keyboard and elsewhere—would suffice. We can do that by subclassing UIApplication to override sendEvent:.

We’ll extend the UIApplicationDelegate protocol with a new message, application:willSendTouchEvent:, and we’ll make our UIApplication subclass send the message to its delegate before handling any touch event.

MyApplication.h

@interface MyApplication : UIApplication
@end

@protocol MyApplicationDelegate <UIApplicationDelegate>
- (void)application:(MyApplication *)application willSendTouchEvent:(UIEvent *)event;
@end

MyApplication.m

@implementation MyApplication

- (void)sendEvent:(UIEvent *)event {
    if (event.type == UIEventTypeTouches) {
        id<MyApplicationDelegate> delegate = (id<MyApplicationDelegate>)self.delegate;
        [delegate application:self willSendTouchEvent:event];
    }
    [super sendEvent:event];
}

@end

We’ll need to make our app delegate conform to the MyApplicationDelegate protocol:

AppDelegate.h

#import "MyApplication.h"

@interface AppDelegate : UIResponder <MyApplicationDelegate>
// ...

AppDelegate.m

@implementation AppDelegate

- (void)application:(MyApplication *)application willSendTouchEvent:(UIEvent *)event {
    NSLog(@"touch event: %@", event);
    // Reset your idle timer here.
}

Finally, we need to make the app use our new MyApplication class:

main.m

#import "AppDelegate.h"
#import "MyApplication.h"

int main(int argc, char *argv[])
{
    @autoreleasepool {
        return UIApplicationMain(argc, argv,
            NSStringFromClass([MyApplication class]),
            NSStringFromClass([AppDelegate class]));
    }
}